you just need two torx bits (can't remember sizes) - one to remove the trim and another to remove the PT/buckle; there's a single lead to disconnect from the PT as well
best to disconnect the battery before, just incase. don't know if there's any danger of them going off but could be extremely dangerous if it does whilst you're holding it
if you re-connect the battery without the PT plugged in, it'll illuminate the airbag warning lamp. not sure if it then goes out if you reconnect the PT - i'd try a search or ask first (ed. presume it does though, as people stick resistors in them - ?)